Hi, yup I had a Final 8'2" that I use ~ 10 sessions. Keep in mind that I am 100kg, so it will be somewhat stabler for you.
This is the fastest board I ever rode. Both for paddling (for its length), and paddling into a wave, and to make fast sections. The combination of narrowness, parallel rails, fast rocker and stiff 100% carbon + PVC sandwich construction makes wonders. In quad setup, you will be astonished at the sections you can make. Basically it gives you a 200% performance ride even in weak conditions, but can hold the power.
And for fitness, the 4 FCS plugs center means you can put a big 3-tabs symmetrical keel fin to help keeping the row in check while pulling hard on the paddle:
This said, I had 9 good sessions with it, but the 10th time it was epic conditions (well overhead) at an outer reef 1 mile offshore. Glassy conditions, but the size of the swell created quite a bit of water movement. It was hell. I couldn't manage to keep upright for more than 30 seconds before falling. I ended up completing a 3 hour session, but prone paddling and getting up just before a coming set. The day after I put it on sale: for me, the added performance was not worth the trouble. I guess it is an age thing: all the 50+ guys I know have resold them or plan to resell. Younger guys seem to have less problems, seems that with age you are slower to react to inbalances. Granted, wider boards are slower to put on the rail... but since we are slower too, that is not really so bothersome.
So, although at your weight it should be manageable, I would advise you to get rather a "curve"(*) in the Gong line: they will have more "carvability" than the Cloud (which is kind of a fish), so can be ridden a more "performance" way (create speed by cranking turns in critical parts of the wave), and be stabler than the final (wider + wider nose). And if you take the SUP only in small conditions and want to do it with your son, the 8' NFA would be a very good choice: pulled-in, rockered tail makes for a great carving/pumpable board, and the wide nose very stable, especially with a toddler up there. Plus the US Box means you can put a big single for flat water, and a thruster setup for surfing. Alas, it does not exist any more in the XTR construction.
Another option would be the AS, the Simmons. It gives you the glide of a longboard in a tight package, with insane stability and nearly no row.
gongsupshop.com/epages/box1707.sf/fr_FR/?ObjectPath=/Shops/box1707/Products/GON6SUPAS710 And if you put your foot on the tail, they turn surprisingly well, but in a different way as a normal SUP: more latency in turns.
Ah, and carrying a toddler on a final... I hope he likes falling in the water often!
You can see a lighter guy with a final (yellow lycra) in the top vid at
www.gong-galaxy.com/forum/viewtopic.php?f=67&t=4520&p=80072&hilit=final+keel (*) as the line is renewed, there are some bargains (aka "Bons Plans") now on the curve XTRs:
gongsupshop.com/epages/box1707.sf/fr_FR/?ObjectPath=/Shops/box1707/Categories/BONS_PLANS/%22Bons%20plans%20SUP%22 a 7'11" and a 8'4" remain. For your weight, the 7'11" 115l will be quite OK, but the 8'4" 125l may be easier with a toddler, but will feel more "gunny" on a wave for you... but still more nimble than the 8'6" Cloud.
Edit: I realize, by re-reading the impression of others on its thread at
www.gongsup.com/forum/viewtopic.php?f=67&t=4520 (most posts in French, some in english) that I may be too negative. Lighter or younger people seem to have less trouble.